Separate but related criminal investigations initiated by Milwaukee County prosecutors have examined events and activities during Scott Walker's time as Milwaukee County executive and as governor. Prosecutors have conducted the probes under the state's "John Doe" statutes that grant extraordinary powers to investigators to compel testimony and maintain secrecy.

The first John Doe investigation, begun in 2010, led to convictions of six Walker aides, associates or appointees on charges ranging from theft from a veteran's group to misconduct in office. The second Doe probe, launched in 2012, looked into coordination between conservative political organizations and Walker and other candidates during recall elections.

The second probe was halted in May 2014 by a federal judge who agreed that the investigation denied one of the conservative groups' its free-speech rights. No charges have been filed in the second investigation. Walker has denied wrongdoing.

Milwaukee County Executive Chris Abele pledged to be nonpartisan in dealing with the release of John Doe emails in coming weeks, at a cost to the county that he says could exceed $500,000.

The county executive's office will soon be in possession of the thousands of documents and will sort through an enormous amount of data to determine what should be made public, Abele said at the Milwaukee Press Club's Newsmaker Luncheon on Wednesday.

The documents were obtained by county prosecutors in the secret investigation into aides and advisers to former County Executive Scott Walker. Abele said the $500,000 cost to the county for reviewing emails and other documents was a ballpark figure that could change based on the volume that is ultimately released.

In May, Reserve Judge Neal Nettesheim ordered that John Doe prosecutors turn over the records seized during the probe to Milwaukee County, which then would respond to open records requests. Nettesheim oversaw the 33-month secret John Doe investigation.

The judge ruled in response to a court filing by the Journal Sentinel, which argued the documents should be turned over. The newspaper argued that county business was conducted through private emails sent by Walker and his county staff.

Abele said his office will honor the public's right to know and reveal any misconduct in a way that also protects people's privacy.

His approach to determining which records are public will potentially mean pulling in staff from county departments as part of the review, and possibly bringing in outside legal help.

The documents will be classified as privileged, immediately shareable or as information that lies in a gray area.

"Being the person who is responsible for determining gray area is a hot potato that nobody wants to be holding, but we will be holding it sometime soon and we try to be as apolitical as possible," Abele said.

Abele said the county would get the information out "as quickly as possible."

The judge has yet to write a formal order for the release of the documents, but Abele said his office has already received open records requests from around the country and has begun to plan how to most efficiently and effectively review and release the information.

Abele also fielded questions related to possible public or private funding for a new arena. He said he is open to discussing any plans for a new arena but was noncommittal on support for any government funding.

He noted the county has many other needs, such as job creation, safe streets, education and paying down debt.

Abele said if a new arena is built, he would like it to be located downtown where it could help stimulate the economy.

He said he thinks other area counties should keep an open mind on the arena, noting several had passed resolutions opposing public funding before any formal proposal had been made.